[TowerTalk] Antenna to Shack Ground Connection

[David Robbins]

Sorry, I have been busy and trying to ignore the recent threads on lightning and grounding, but this one needs to be debunked... again.

"Lots of folks think lightning rods (and other structures such a towers 
etc.) are intended to attract lightning to protect other objects from 
being hit. Not so, gentle reader, as the primary purpose of lightning 
rods is to drain away static charges such as accumulate and thereby 
prevent a lightning strike. If the grounded system is hit by lightning 
then the protection system has failed its primary goal. A secondary 
consideration is surviving the strike so as to continue with its primary 
purpose of draining charge and preventing strikes in the immediate area."

No, there is no way a lightning rod system, even if using those fancy porcupines on a stick, will ever dissipate enough
charge to prevent a structure getting hit.  if that were the purpose there would be no need for heavy conductors from 
lightning rods as the current during the concentration of charge on the ground under a convective cell is pretty small.  
just think, how much current does it take to make your hair stand on end?  or for the tiny corona and sparks from pine
needles or sharp points on a structure??? its TINY... and even an entire patch of a forest going into corona trying to
dissipate charge doesn't prevent it from being hit.  lightning rods are designed to be the preferred point that gets hit,
they do that by having a sharp point that goes into corona easily and initiates the upward streamer where the downward 
moving leader makes its connection to ground thus triggering what you see as lightning.

Also note that the old 'rolling ball' or '30 degree angle' for shielding under a structure or wire is not reliable.  there are
many lightning triggered camera systems that have caught lightning striking power lines directly under a shield wire
and buildings getting hit on their side instead of on top.  there is a strong random component in the movement of the
downward leaders that make the final attachment point VERY hard to control or predict.